Anodizing is a method of providing a protective anodic oxide film on a metal substrate, often used in industry to provide a protective and sometimes cosmetically appealing coating to metal parts. When subjected to any of a number of manufacturing processes, such as laser marking or other thermal operations, however, anodic oxide films can crack due to internal stresses. Machining and handling can also form cracks or crack-like defects. Substrate geometry can also increase the likelihood of an overlying anodic oxide film to have cracks or crack-like defects. For example, anodic films formed on corners or convex curvatures of a substrate can develop cracks along these corners and curvatures.
Although stress-induced cracks are generally very small, if the cracks span the entire thickness of an anodic oxide film, they can present pathways for water or other corrosion-inducing agents to reach the underlying metal substrate through an otherwise protective metal oxide film. Over time and repeated exposure to water or other corrosion-inducing agents during the service life of a part, corrosion of the underlying metal substrate can quickly escalate and further compromise the protective properties of the anodic oxide film. What is needed, therefore, are manufacturing methods for repairing cracks within anodic oxide films, thereby enhancing the corrosion protection of the anodic oxide films.